The deaths of celebrities such as Michael Jackson, the release of Google Wave and the marital strife of Sandra Bullock are among the topics which have been used as themes for these attacks in the past. Just about any high-profile breaking news story is fodder for the crooks, so it came as little surprise that the deaths of 39 people in the Moscow metro suicide bombings on Monday have also become themes for the latest run of black-hat SEO techniques.

Blackhat SEO kits are used to create and manage an search engine manipulation attack. These kits generate manipulated pages stuffed with erroneous keywords, designed to appear prominently in search engine results but which misdirect users to rogue sites.

SEO kits also create networks of thousands of cross­linked pages containing this search­-friendly content on hot­ trending topics, hosted on compromised, legitimate websites. Often these kits will be automatically updated with information about the latest breaking news stories by consulting resources such as Google Trends.

These blackhat tactics are commonly used to point surfers searching for information about popular subjects towards scareware portals that inundate users with bogus security alerts in a bid to trick them into paying for a bogus security product, or installing further malicious code.

Search engine poisoning attacks rely on the need to feed content to search engine crawlers (for subsequent indexing), while at the same time redirecting users who land on the webpage to a malicious site. Most blackhat SEO kits can spot the difference between a search engine visiting their site to crawl for content, a surfer visiting the site via a search engine link, and a computer user visiting the site directly.

Often exploits are redirections that are only triggered when a surfer visits the site via a search engine. The tactic is designed to help keep the hacker misuse of often legitimate sites under the radar of site admins.

Sophos reckons URL filtering and content inspections offer effective protection for businesses against SEO attacks. "Malware distribution through SEO may sound hard to block because of the apparent authenticity of the SEO web pages but there are some effective measures that companies can take to protect themselves," Howard explains.

"By adding detection for the payload, as well as diligent monitoring and filtering in-bound content, network managers can thwart an attack before it reaches the user. Providing detection for all relevant components provides the most effective protection.”

The research paper, Poisoned search results: How hackers have automated search engine poisoning attacks to distribute malware, can be found here (pdf). ®